1. Field of the Invention
The subject invention relates to synchronous rectification, and more particularly, to a method of deriving the individual switching current signal for the currents flowing in each switch of the synchronous rectifier switches utilized in a three-level Vienna-type active rectifier.
2. Description of Related Art
Synchronous rectification is a concept that has been applied in the past, particularly in DC-DC converters at low output voltage levels. In those converters where conventional circuit topologies were utilized, a voltage drop of 0.4 V to about 1.0 V in the output rectifier is common and would be converted into a significant loss, since the output voltage of a typical DC-DC power converter in these applications is usually only about 1.0 or 2.0V.
Synchronous rectification involves the use of a power MOSFET connected in parallel with a diode, wherein the MOSFET is configured to be turned on when the diode is conducting, so that current flow is re-directed through the MOSFET. Since the MOSFET operates with lower resistance than the diode, the voltage drop across the circuit will be lower and more efficient.
Given the efficiencies associated with synchronous rectification, it would be beneficial to apply this principle to a full power circuit of a unidirectional active rectifier, also known as a Vienna Rectifier, in order to reduce the static losses across the circuit. This would be particularly advantageous in power inverter/converter topologies employed in aerospace applications, wherein switching speed and efficiency are sought after goals.
It is also known that the currents flowing in a synchronous rectifier switch must flow in the direction of the diode, not in a reverse direction, due to unidirectional power flow restrictions in aircraft power systems. Because of this restriction, it would be beneficial to know the currents flowing in the synchronous rectifier switches of the Vienna Rectifier in order to prevent these switch currents from flowing back to their source.